Method of making a dunnage platform

ABSTRACT

A dunnage platform is in the general shape of a rectangular slab with legs extending form one side. The dunnage platform is made from an expanded polystyrene core. A chemical combination process is used to chemically combine portion of the core proximal to its surface with high impact polystyrene. In a first of two parts of the combination process, the core is placed in a forming mold with one of its two sides and two thirds of its thickness extending therefrom. A heated sheet of high impact polystyrene is brought into contact with the portion of the core extending from the mold. In a similar manner, the other of the two sides of the core is made to extend from the forming mold for contact with a heated sheet of high impact polystyrene.

CLAIM OF PRIORITY

This application is a continuation of and claims priority to pendingU.S. patent application Ser. No. 13/240,839, filed Sep. 22, 2011, whichis a continuation of U.S. patent application Ser. No. 12/464,283, filedMay 12, 2009 which issued as U.S. Pat. No. 8,142,589 on Mar. 27, 2012,which application is a continuation of U.S. patent application Ser. No.11/617,578, filed Dec. 28, 2006 which issued as U.S. Pat. No. 7,544,262on Jun. 9, 2009, which application is a continuation of U.S. patentapplication Ser. No. 11/490,372, filed Jul. 20, 2006 which issued asU.S. Pat. No. 7,611,596 on Nov. 3, 2009, which application is acontinuation of U.S. patent application Ser. No. 10/921,903, filed Aug.20, 2004 which issued as U.S. Pat. No. 7,128,797 on Oct. 31, 2006, whichapplication is a divisional of U.S. patent application Ser. No.10/166,988, filed Jun. 11, 2002, and which issued as U.S. Pat. No.6,786,992 on Sep. 7, 2004. The above applications and patents are hereinexpressly incorporated by reference in their entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention is in the general field of load-bearing structures and,more particularly, is a load bearing structure made from an expandedpolystyrene core that is chemically combined with high impactpolystyrene.

2. Description of the Prior Art

A shipping pallet is a well known load-bearing, moveable platformwhereon articles are placed for shipment. The pallet usually is loadedwith a multiplicity of items, such as cartons or boxes. The loadedpallet is movable with either a pallet truck or a forklift

There is a nine billion dollar market for pallets in the United States.There is a thirty billion dollar world wide market. Approximately ninetypercent of these markets is for pallets made from wood.

The weight of the wood pallet is in a range of forty to seventy pounds.Therefore, the weight of a cargo shipped on the wood pallet is reducedby from forty to seventy pounds to provide for the weight of the woodpallet.

It should be understood that injuries caused by wood splinters and nailsare frequent occurrences among people who handle the wood pallet.Additionally, disposal of the wood pallet at the end of its useful lifeis a threat to the environment.

There has been concern among nations about the use of the wood palletcausing an import of wood-boring insects, including the Asian LonghornedBeetle, the Asian Cerambycid Beetle, the Pine Wood Nematode, the PineWilt Nematode and the Anoplophora Glapripwnnis. Exemplary of damagecaused by imported insects is the fate of the Chestnut Tree in theUnited States. There was a time when it was said that a squirrel couldcross the United States on Chestnut Tree limbs without ever touching theground. Insect infestation has caused the extinction of the ChestnutTree in the United States.

Therefore, the wood pallet's weight, the injuries that it causes, itsthreat to the environment and the possibility of it causing animportation of wood-boring insects militates against the use of the woodpallet. As explained hereinafter, there is an attractive alternative tothe wood pallet.

SUMMARY OF THE INVENTION

An object of the invention is an easily movable load bearing structurethat is not likely to carry wood-boring insects.

Another object of the invention is a movable load bearing structure thatdoes not have splinters and nails that may cause injury.

According to the present invention, a dunnage platform has an expandedpolystyrene core with a region proximal to its surface that ischemically combined with a high impact polystyrene.

Because of a chemical combination of components, comparing the corebefore the chemical combination to the dunnage platform that is formed,there is an increase in strength to weight ratio of as much as 1000:1that allows the dunnage platform to carry loads comparable to loadscarried by a wooden pallet. The dunnage platform does not support insectlife and does not have splinters and nails that cause injury.

Other objects, features and advantages of the invention should beapparent from the following description of a preferred embodimentthereof as illustrated in the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a perspective view of a top side of a core of a dunnageplatform that is in accordance with the invention;

FIG. 2 is a perspective view of a bottom side of the core of FIG. 1;

FIG. 3 is a perspective view of a forming mold;

FIG. 4 is a side elevation of the core of FIG. 1 within the forming moldof FIG. 3 positioned below a clamping frame with a first high impactpolystyrene sheet clamped therein in preparation for a first of twoparts of a chemical combination process;

FIG. 5 is a perspective view of the clamping frame and the first sheetof FIG. 4;

FIG. 5A is a plan view of the first sheet of FIG. 3;

FIG. 5B is a view of FIG. 5 taken along the line 5B-5B;

FIG. 6 is a side elevation of the core of within the forming mold ofFIG. 3 positioned below the clamping frame after the first sheet hasbeen heated;

FIG. 7 is a side elevation of the clamping frame seated upon a marginalportion of the bottom side of the core;

FIG. 8 is a perspective view of the bottom side wherein holes have beendrilled through strengthened polystyrene;

FIG. 9 is a side elevation of the core within the forming moldpositioned below the clamping frame with a second high impactpolystyrene sheet clamped therein in preparation for the second part ofthe chemical combination process;

FIG. 10 is a side elevation of the core within the forming moldpositioned below the clamping frame after the second sheet has beenheated; and

FIG. 11 is a side elevation of the clamping frame of FIG. 10 seated upona marginal portion of the top side of the core.

DESCRIPTION OF THE PREFERRED EMBODIMENT

As shown in FIGS. 1 and 2, an expanded polystyrene core 10 is in thegeneral shape of a rectangular slab with an edge 12 (FIG. 1) that has awidth 14 which is approximately 1¾ inches. The core 10 has a smoothtopside 16 that is on the order of forty eight inches long and fortyinches wide. A bottom side 18 (FIG. 2) of the core 10 includes legs20-28 approximately four inches long extending therefrom.

The edge 12 is proximal to ma spaces 42, 44, 46, 48 on the bottom side18. The marginal spaces 42, 44, 46, 48 separate the legs 26-28, the legs20, 2326, the legs 20-22 and the legs 22, 25, 28, respectively, from theedge 12.

Because the core 10 is made from expanded polystyrene, it does not havesufficient structural strength to be useable as a load bearing platform.A dunnage platform with sufficient strength is formed by chemicallycombining a region of the core 10, proximal to its surface, with a highimpact polystyrene. Expanded polystyrene and high impact polystyrene arewell known. The dunnage platform described hereinafter has substantiallythe same dimensions as the core 10.

A first of two parts of a chemical combination process causes portionsof the expanded polystyrene proximal to the bottom side 18 to bechemically combined with the high impact polystyrene to formstrengthened polystyrene. Additionally, a portion of the expandedpolystyrene that is proximal to the edge 12 and in a proximalrelationship to the bottom side 18 is chemically combined with the highimpact polystyrene to form the strengthened polystyrene.

As shown in FIG. 3, a forming mold 50 has rectangularly disposed walls52-55 that define an interior 56 and a top surface 58. An interiorsurface 56U of the walls 52-55 outline a portion of the interior 56 thatis complimentary to a shape of the core 10 outlined by the edge 12.

An interior of the walls 52-55 form a shelf 60 that extends around theinterior 56. The shelf 60 has a surface 62 that is parallel to thesurface 58. For reason's explained hereinafter, a displacement betweenthe surfaces 58, 62 is less than one half of the width 14 (FIG. 1). Inthis embodiment, the displacement between the surfaces 58, 62 is onethird of the width 14.

As shown in FIG. 4, the mold 50 is moveable in a direction of the arrows63. The core 10 is retained within the mold 50 with a marginal portionof the top side 16 that is proximal to the edge 12 is seated upon thesurface 62 (FIG. 3) whereby the top side 16 is maintained within themold 50. Since the distance between the surfaces 58, 62 is one third ofthe width 14, two thirds of the edge 12 extends from the mold 50.Additionally, the bottom side 18 extends from the mold 50.

A fixedly positioned clamping frame 64 has a first high impactpolystyrene sheet 67 clamped therein. A heater 68 is positioned proximalto the frame 64.

As shown in FIG. 5, the frame 64 is made from an upper rectangular frame74 and a lower rectangular frame 76 that are held together by aplurality of screws 78. The length and width of the upper frame 74 issubstantially equal to the length and width, respectively, of the lowerframe 76.

As shown in FIGS. 5A, and 5B, with the screws 78 not tightened, edges ofthe sheet 67 (FIG. 5A) are inserted between the frames 74, 76 (FIG. 5B)in much the same way that edges of a bed sheet are inserted between amattress and a box spring. At corners of the frames 74, 76, the sheet 67is folded in much the same way that edges of the bed sheet are folded toform what is known as a hospital corner and inserted between the frames74, 76. When the edges and corners of the sheet 67 are inserted, thesheet 67 extends in a plane that causes it to cover a side 80 of theframe 76. Thereafter, the screws 78 are tightened whereby the sheet 67is fixedly maintained in the frame 64.

As shown in FIG. 6, in the first part of the process, the heater 68heats the sheet 67 to a temperature in a range of 293.degree. F. to375.degree. F. In response to being heated, the sheet 67characteristically sags. After the sheet 67 is heated, the heater 68 isremoved and the mold 50 is moved in a direction of the arrows 63.

It should be understood that when the sheet 67 is heated, it becomesfragile. Because the frame 64 is fixedly positioned, a risk of damage tothe sheet 67 is minimized.

As shown in FIG. 7, the mold 50 is moved until a portion of the heatedsheet 67 that covers the side 80 (FIG. 5B) is seated upon the surface 58(FIG. 3). The mold 50 is connected to a vacuum pump 84 through an airbox 86 and a connector line 88.

It should be understood that the core 10 is porous. When the vacuum pump84 operates, air may pass through the core 10, from the top side 16, tothe pump 84. The heated sheet 67 is not porous, thereby causing oneatmosphere of air pressure that draws the heated sheet 67 onto thebottom side 18 and the two thirds of the edge 12 that extends from themold 50.

The expanded polystyrene proximal to the bottom side 18 and proximal tothe two thirds of the edge 12 that extend above the mold 50 chemicallycombine with the high impact polystyrene of the sheet 67 to form thestrengthened polystyrene. The strengthened polystyrene is not porous.The side 18 and the legs 20-28 with the strengthened polystyreneproximal to their surface are hereinafter referred to as a side 18C withlegs 20C-28C, respectively.

As shown in FIG. 8, because the strengthened polystyrene is not porous,a plurality of holes 90 are drilled into the side 18C to approximate theporosity of expanded polystyrene.

As shown in FIG. 9, in a second part of the process, the side 18C isretained within the mold 50 with the marginal spaces 42, 44, 46, 48(FIG. 2) seated upon the surface 62. Since the displacement between thesurfaces 58, 62 is one third of the width 14, two thirds of the edge 12extends from the mold 50. It should be understood that during the secondpart of the process, the two thirds of the edge 12 that extends from themold 50 includes one third of the edge 12 that did not extend from themold 50 during the first part of the process.

The frame 64 frames a second high impact polystyrene sheet 94, similarto the sheet 67. The frame 64 with the sheet 94 is fixedly positionedabove the mold 50. The heater 68 is positioned proximal to the fame 64.

As shown in FIG. 10, the heater 68 is used to heat the sheet 94 and theframe 64 mold 50 is moved in a direction of the arrows 63 in a mannersimilar to that described in connection with the first part of theprocess.

As shown in FIG. 11, the mold 50 is moved until a portion of the sheet94 that covers the surface 80 (FIG. 5B) is seated upon the surface 58.Because of the holes 90 (FIG. 8), when the vacuum pump 84 operates, airmay pass to the pump 84. However, the sheet 94 is not porous, therebycausing one atmosphere of air pressure to draw the sheet 94 onto the topside 16. Since the sheet 94 is connected to the frame 64 as describedhereinbefore, all portions of the core 10 that extend above the mold 50contact the sheet 94.

In accordance with the second part of the process, the expandedpolystyrene proximal to the portions of the surface of core 10 thatextends from the mold 50 chemically combines with the high impactpolystyrene of the sheet 94 to form the strengthened polystyrene.Moreover, because the displacement between the surfaces 58, 62 is lessthan one half of the width 14, the strengthened polystyrene is formedproximal to the entire edge 12.

The dunnage platform formed by the process weighs approximately eightpounds and can carry an approximately 3500 pound load.

As shown in FIG. 8 the legs 20C-22C, the legs 23C-25C and the legs26C-28C are arranged in parallel columns 95-97, respectively. Thecolumns 95-97 are spaced so that tines of a fork lift can fit betweenthe columns 95, 96 and between the columns 96, 97. Accordingly, with thetines parallel to the columns 95-97, the fork lift can lift the dunnageplatform from either of two sides.

Similarly, the legs 20C, 23C, 26C, and the legs 21C, 24C, 27C and thelegs 22C, 25C, 28C are arranged in parallel rows 98-100, respectively,that are orthogonal to the columns 95-97. The rows 98-100 are spaced sothat tines of a fork lift can fit between the rows 98, 99 and betweenthe rows 99, 100. Accordingly, with the tines parallel to the columns98-100, the fork lift can lift the dunnage platform from either of twosides.

While the invention has been particularly shown and described withreference to a preferred embodiment, it should be understood by thoseskilled in the art that changes in form and detail may be made thereinwithout departing from the spirit and scope of the invention.

1. A method of making a dunnage platform comprising: providing a coremade from an expanded polymer for defining the shape of the platform,said core having a dimension, a first side and a second side separatedby an edge; heating a first thermoplastic sheet having a dimensionlarger than the dimension of the core, said thermoplastic sheet beingheld tautly prior to heating; placing said first heated thermoplasticsheet on top of said first side of said core while the second side ofsaid core is uncovered by a thermoplastic sheet; and combining saidheated first thermoplastic sheet with at least a region of said firstside and at least a part of said edge of said core to form a dunnageplatform with sufficient load bearing strength; wherein said at least aportion of said first side and at least a part of said edge are exposedduring placement of said first heated thermoplastic sheet on top of saidfirst side of said core.
 2. The method of claim 1 wherein said firstthermoplastic sheet is heated until it sags prior to being placed onsaid first side of said core.
 3. The method of claim 1 wherein saidcombining comprises applying a vacuum to draw said first heatedthermoplastic sheet onto said first side of said core.
 4. The method ofclaim 1 wherein said core is retained in a forming mold to expose saidfirst side, and at least part of said edge.
 5. The method of claim 1wherein said first thermoplastic sheet is held in a clamping frame. 6.The method of claim 1 further comprising: retaining said core combinedwith said first thermoplastic sheet in a forming mold having an interiorthat is complementary to a shape of said core to expose the second sideand at least a portion of said edge of said core; heating a secondthermoplastic sheet and placing said heated second thermoplastic sheeton top of said second side of said core.
 7. A method of making a dunnageplatform comprising: providing a core made from an expanded polymer fordefining the shape of the platform, said core having a dimension, afirst side and a second side separated by an edge; heating a firstthermoplastic sheet having a dimension larger than the dimension of thecore, a portion of said first thermoplastic sheet being held by aclamping frame; placing said first heated thermoplastic sheet on top ofsaid first side of said core while the second side of said core isuncovered by a thermoplastic sheet; and combining said heated firstthermoplastic sheet with a region of said first side and a part of saidedge; wherein said first side and at least a part of said edge areexposed during placement of said first heated thermoplastic sheet on topof said first side of said core.
 8. The method of claim 7 wherein saidclamping frame comprises an upper frame attached to a lower frame. 9.The method of claim 7 wherein said first thermoplastic sheet is heateduntil it sags prior to combining with said core.
 10. The method of claim8 wherein said first thermoplastic sheet is clamped between said upperand said lower frame about its edges.
 11. The method of claim 7 whereinsaid combining is effected by heating said first thermoplastic sheet ata temperature range of 293° F. to 375° F.
 12. The method of claim 7further comprising: retaining said core combined with said firstthermoplastic sheet in a forming mold having an interior that iscomplementary to a shape of said core to expose the second side and atleast a portion of said edge of said core; heating a secondthermoplastic sheet; and combining said heated second thermoplasticsheet with said second side and a part of said edge of said core. 13.The method of claim 12 where said second thermoplastic sheet covers saidsecond side of the core and at least a portion of said edge.
 14. Amethod of making a dunnage platform comprising: providing a core madefrom an expanded polymer for defining the shape of the platform, saidcore having a dimension, a first side and a second side separated by anedge; heating a first high impact polystyrene sheet having a dimensionlarger than the dimension of the core, said high impact polystyrenesheet being held tautly prior to heating; placing said first heated highimpact polystyrene sheet on top of said first side of said core whilethe second side of said core is uncovered by a thermoplastic sheet; andcombining said heated first high impact polystyrene sheet with saidfirst side and a part of said edge of said core; wherein said first sideand at least a part of said edge are exposed during the placement ofsaid first heated high impact polystyrene sheet on top of said firstside of said core.
 15. The method of claim 14 wherein said high impactpolystyrene sheet is being held by at least a portion of its edge. 16.The method of claim 14 wherein said first high impact polystyrene sheetis heated at a temperature range of 293° F. to 375° F.
 17. The method ofclaim 14 wherein said combining comprises applying a vacuum to draw saidheated first high impact polystyrene sheet onto said first side of saidcore.
 18. The method of claim 14 wherein said first high impactpolystyrene sheet is held in a clamping frame about at least a portionof its edges.
 19. The method of claim 14 wherein said first side of saidexpanded core and more than half of said edge is covered by said firsthigh impact polystyrene sheet.
 20. The method of claim 14 wherein saidproviding comprises providing said core in a forming mold having aninterior that is complementary to a shape of said core.